class ProgramingLanguage {
  final String name;
  final int age;
  ProgramingLanguage(this.name, this.age);
  ProgramingLanguage.namedFunc(this.name, this.age);

  developforComputer() {
    print('developforComputer');
  }
}

class Swift extends ProgramingLanguage {
  final String iOS;

  Swift(String name, int age, this.iOS) : super(name, age);
  Swift.namedFunc(String name, int age, this.iOS) : super.namedFunc(name, age);

  @override // 建议加上
  developforComputer() {
    super.developforComputer();
    print('developforComputer using Swift');
  }

  developforiOS() {
    print('ddevelopforiOS');
  }
}
